Sub-surface irrigation is 'radical' approach

A radical approach to irrigation is making a deep impression on thousands of acres of Georgia cropland and could make a similar imprint on Alabama fields.

Sub-surface irrigation is radical in the sense that moisture is brought down to the parts of the plant that need it most — the roots — down as far as 9 to 12 inches between crop rows.

For many growers, the approach offers tremendous benefits, says Calvin Perry, a University of Georgia research and Extension engineer who discussed the merits of irrigation at the Precision Agriculture and Crops Field Day at the Isbell Farm located in the northwest Alabama community of Cherokee.

No, it’s not for everybody, says Perry, but it can work — and work well — for some growers, especially those who can afford the costs of implementing and maintaining the system over time.

It is especially useful for farmers who are trying to irrigate an irregularly shaped area where pivots don’t work well.

“It puts out the water very efficiently,” Perry says. “You don’t have that evaporative loss because you’re putting it right down into the root zone.” By applying water directly to the roots, this approach also cuts down on weed problems by reducing weed growth and germination.

And with water being applied directly to the roots, the crop canopy remains drier — an added safeguard against disease pressure.

Soil crusting also is reduced.

And without a pivot in the way, farmers are in a better position to undertake field operations.

“With sub-surface irrigation, you can continue right on with these operations because the sub-surface system isn’t in the way to interfere,” Perry says.

But like most farming technologies, sub-surface irrigation, while offering many advantages, is no panacea.

While there’s undoubtedly much merit behind the old saying “out of sight, out of mind,” drip tape, while out of sight, doesn’t necessarily guarantee peace of mind.

“It’s out of sight, which is one advantage, but, then again, it’s out of sight,” says Perry. “And it’s hard to know when you have problems, such as rodents chewing on your lines.”

And when serious problems do occur, sub-surface systems can be considerably more unforgiving than a relatively more low-maintenance center pivot system.

Extra caution is also required during harvesting, especially when sub-surface irrigation is used with peanuts, though this can be readily addressed through precision farming methods.

Using autosteering to lay down the tape and to conduct other routine farming chores would help farmers go a long way toward avoiding this calamity, Perry says.

“That way, you know it’s perfectly straight,” he says. “You know where it is and when you do your tillage and other operations, you use the autosteer to keep off the drip tape.”

With adequate maintenance, Perry says there is no reason why tape could not last as long as a pivot system — as long as 10 and even 20 years, in some cases.

“If there’s no damage and you avoid rodents, you can get that sort of lifespan out of the tape.”